Secondary-Amine-Terminated Siloxane-Modified Polyaspartic Polyurea With Enhanced Durability and Corrosion Resistance

To enhance the overall properties of polyaspartic polyurea (PAEU) coatings, a siloxane -modified PAEU (SiPU) series was synthesized using diethyl maleate-alkylated aminopropylsilane (DM-APTMDS) as a modifier. Systematic characterization and performance tests revealed that the incorporation of DM-APTMDS improved thermal stability, lowered the glass transition temperature, and promoted microphase separation. These structural modifications resulted in significantly enhanced adhesion (up to 8.49 ± 0.44 MPa), flexibility (elongation at break of 149%), and hydrophobicity (water contact angle of 99.4°). Specifically, at 21 wt% DM-APTMDS, the coating demonstrated superior durability against chemical attack, UV aging, freeze–thaw cycling, achieving the minimum corrosion current density (7.21 × 10 −8 A/cm 2 ) and highest protection efficiency (89.82%). This optimal formulation achieved a well-balanced combination of toughness, hydrophobicity, adhesion, and anticorrosion performance. This work provides important theoretical and practical guidance for designing high-performance, durable polyurea protective coatings.